1. Field of Invention
This invention relates to sequencing valves and more particularly to sequencing valves which selectively direct a source of fluid to one or more of a plurality of use outlets, which operate in optimum manner for the fluid system at hand, is configured to provide anti-siphon protection when connected to municipal water supplies, and which achieve these functions while being of minimum size and weight, having a minimum of moving parts which are easy to maintain.
2. Description of the Prior Art
Several different approaches have been made to provide a sequencing valve, but none have provided the features with the simplicity and compactness of the improved type disclosed herein. Classically, irrigation systems use a plurality of selectively positioned fluid distribution valves controlled remotely, either electrically or hydraulically, but such plural valve systems are more costly to install and maintain in view of the amount of apparatus and the total number of moving parts utilized. Sequencing valves which are directly controlled by solenoids have also been utilized, but have a higher pressure loss and greater complexity. Flow turbine operated valves have also been utilized but are overly complex, and subject to contamination damage, as well as lacking flexibility of timing and selection of individual zones.
Sequencing valves which utilize fluid pressure variation to switch the valve discharge port being supplied have found great acceptance. Examples of the prior art in this category, which my invention described hereinafter constitutes an improvement over, are U.S. Pat. Nos. 2,642,022; 2,666,450; 2,833,309; 3,124,162; 3,369,565; 3,431,933; 3,472,265; 3,785,391; and my earlier patents Nos. 3,460,560; 3,524,470; 3,635,237; 3,747,620 and 3,924,652.